A gas circuit breaker of a puffer type or the like is used for a gas-insulated switchgear installed in a substation or a switching station. The gas circuit breaker includes a container air-tightly filled with an insulating gas, in which a fixed electrode part and a movable electrode part are arranged to face each other in an engaging/separating manner under the insulating gas atmosphere. The gas circuit breaker further includes an operating mechanism outside the container, i.e., in the air. The operating mechanism refers to a mechanism to operate the movable electrode part by transferring an operating force to the movable electrode part in the container.
The gas circuit breaker further includes a plurality of rotatable links and linearly movable rods configured to transfer and convert a displacement output, which is an operating force of the operating mechanism, to a displacement of the movable electrode part. In addition, if the displacement output from the operating mechanism is shorter than the displacement of the movable electrode part, a lever to amplify the displacement output from the operating mechanism may be connected to the rods. The connection of the lever to the rods makes it possible to secure a movement stroke of the rods by shaking of the lever.
An operating rod and a seal rod may be used as a linearly movable rod. The operating rod is a rod configured to provide a driving force to the movable electrode part and may be arranged in its entirety in the container.
On the other hand, the seal rod is a rod configured to penetrate through a partition of the container and may be slidably attached to a seal bearing (having a gas sealing function) fixed to the partition of the container.
The conventional gas circuit breaker has the following problems. In this gas circuit breaker, since the combination of rotatable links and linearly movable rods is used to transfer the operating force of the operating mechanism to the movable electrode part, a component force is generated in an operating axial line of the rods in a direction perpendicular to a movement direction of the rods.
In particular, when the displacement amplification lever is connected to the rods, a large component force is generated since an inertial force of the lever is heavily loaded on the rods. This component force exerts on a portion slidably supporting the rods to increase a frictional force exerted on the rods, which results in a low operating speed of the rods.
In addition, a bending stress may act on the rods due to the component force, which may result in a deformation of the rods. For the purpose of avoiding such rod deformation, a sectional area (section modulus) of the rods tends to be large. However, such upsizing of the rods increases weight of the rods in proportion, which causes the operating speed of the rods to be lower.
It is essential to secure a certain level of operating speed of the rods since it has a direct effect on an opening speed of the gas circuit breaker. Accordingly, a large-scaled operating mechanism consuming more driving energy has been conventionally employed in order to secure the operating speed of the rods. However, such large scaling of the operating mechanism leads to increase in costs and size of the entire gas circuit breaker.